PORTLAND, Maine — On April 23, heavy rains pounded Portland. The next day, many of the city’s most recognizable water bodies were the color of sewage.

“I look out my window at the bay and it’s brown,” said Casco Baykeeper Joe Payne, whose Friends of Casco Bay headquarters is across Portland Harbor in South Portland. “When I see just the visuals from a storm like that and know that millions and millions of gallons of pollutants and sewage and runoff went into the bay it makes me anxious and saddened.”

Two decades after the city of Portland entered into a consent agreement with federal environmental regulators to systematically eliminate combined sewer-stormwater overflows, or CSOs, signs of the overflows are still prominent after every major rainstorm.

Equally striking for Portlanders is the estimated $170 million price tag tied to the next 15 years of working on the problem, a cost that comes on top of $94 million spent or scheduled to be spent on sewer system fixes between 1993 and 2014, and which is expected to double or triple sewer bills for many local ratepayers.

Scariest of all is the acknowledgement that there’s no end in sight for either the polluting overflows or the crushing expenses associated with reducing them. By the time the next wave of projects is scheduled to conclude in 2029, the city annually will continue to pour 87 million gallons of contaminated water and sewage into Back Cove and Portland Harbor.

In CSOs, rainwater enters into underground sewer pipes. When the combined volume is more than city treatment facilities can handle, it bypasses the sanitary checkpoints and spills into Casco Bay and other bodies of water. The discharges carry oils and chemicals washed from the city streets as well as excrement from homes and businesses tied into the sewer system.

Even where the water isn’t brown, Payne said, the impact of the overflows can be tested. After one recent storm he navigated his boat out into the bay near Fort Gorges and tested for salinity. Payne said he was forced to go down six feet of depth on a open ocean bay before he found salt water.

That’s six feet of freshwater, flushed into the bay through runoff and sewer overflows, riding on top of what is supposed to be ocean water. Payne said he was surprised, and most other people are as well when he tells them of the experiment.

“Raw sewage can contain parasites and pathogens of concern that can come back to us on our plate or while swimming,” said Payne, who last week was given a lifetime achievement award by the Environmental Protection Agency. “In fresh water, you get into drinking water issues. Here, people get concerned about fecal matter in seafood. Our communities are past the point where anyone thinks it’s OK to dump raw sewage into the bay, and people are shocked by it — people don’t know that it’s happening.”

In recent years, a ‘concerted effort’

The Maine Department of Environmental Protection this week released its annual statewide CSO report, revealing that Portland in 2011 discharged 496.3 million gallons of runoff and sewage into water bodies through combined sewer overflows.

That represents 44 percent of the state’s entire CSO volume. Portland has 120 miles of piping in which stormwater and sewage are combined, compared with 68 miles of dedicated stormwater pipes and 107 miles of dedicated sewer pipes.

“Obviously Portland is our largest city in the state, and rightly or wrongly it’s our largest CSO contributor in the state,” said David Breau, the department’s CSO coordinator. “They have more sewer pipe in the ground. Therefore, they collect more water and combined stormwater and wastewater.”

The next closest communities on the list are Bangor and Brewer, with 146 million and 140 million gallons discharged in 2011, respectively.

But while the most recent numbers are daunting, they represent a great leap forward for Portland, which discharged more than 1.8 billion gallons as recently as 2006, according to DEP data.

Even those figures seem sparkling when compared to Portland’s anecdotal history of water pollution.

“We’ve got reports going back to the 1850s and 1870s, where they were trying to get rid of the ‘nuisance’ of Back Cove, because it was all sewage,” city engineer Bradley Roland said.

Payne noted that Portland didn’t even build a sewage treatment plant until the late 1970s, “so all the city’s sewage went into the bay” prior to that time. He said a six-foot-wide wooden trough, once used to carry untreated effluent, can still be seen stretching out into Portland Harbor from underneath Long Wharf during low tides.

“Think about running around Back Cove 20 or 30 years ago,” said Sean Mahoney, director of the Maine branch of the Conservation Law Foundation. “It would not have been a very pleasant experience, especially after a heavy rainstorm. The Presumpscot River would peel the paint off of people’s houses it was so bad. That’s the type of thing not many people may remember.”

Mahoney said the Conservation Law Foundation recognized Portland was not in compliance with the federal Clean Water Act and began a dialogue with the city in 1991. He said the city averted a potential lawsuit filed by the foundation by entering into a consent agreement with state regulators, lining up a plan to reduce CSOs over time.

Early on, environmental watchdogs such as the Conservation Law Foundation and Friends of Casco Bay argued the city was falling consistently behind schedule. Payne said that Portland took eight years to accomplish the plan’s first three years’ worth of work.

“I think everyone would agree the city did not meet a lot of the early deadlines called for in the consent decree, and that was, quite frankly, disappointing,” Mahoney said. “But over the last several years the city has made a concerted effort to address the issues listed in the consent decree in a manner that’s very reasonable.”

Since 1993, the city has completed more than 100 CSO abatement projects, eliminated 11 of its 43 overflow points and reduced average overflow volumes by more than 42 percent.

“If you didn’t have an appreciation for the distance we’ve already traveled in cleaning up Casco Bay or Back Cove or our river, you do a disservice to the time and money people have spent to get us to where we are today,” Mahoney said. “The idea that people can swim at East End Beach on a regular basis now [is recent] — 40 years ago, you did so at risk to your health.”

New ‘stormwater fee’ proposed

The city of Portland is finishing projects associated with what is known as Tier II of its ongoing CSO plan. Tier III — the $170 million phase of the overall work — is due to begin in 2014. The aim of the Tier III projects will be to eliminate CSOs into the Fore River, cut Back Cove CSOs from 416 million gallons annually to 70 million gallons and reduce overflows into Portland Harbor from 145 million gallons per year to 17 million gallons.

In addition to strategic “green solutions” to prevent stormwater from ever running into the drains — such as strategically placed gardens and porous pavement to absorb rain where it falls — Tier III projects include several massive underground storage tanks meant to gather the first inch of rain from any storm. Such tanks, to be located near Baxter Boulevard, Marginal Way, West Commercial Street and the Fore River pump station, would hold rainwater and runoff until a storm passes, then route the additional water through the treatment facilities when the weather’s dry and there’s plenty of capacity.

The Tier III work would leave Portland’s total overflow level at 87 million gallons per year after about 35 years and $264 million in investments. In comparison, the town of Rockland entirely eliminated its CSOs by spending about $6.4 million over about a decade.

“You just can’t do enough projects to eliminate them all [in a city Portland’s size],” city engineer Bradley Roland said.

Over the past year, a city task force chaired by City Councilor Ed Suslovic was charged with developing a plan to raise the next $170 million.

In March, the task force officially recommended the creation of a new stormwater fee to be added to existing sewer fees. Under the plan being proposed, 50 percent of the $170 million in costs will be raised through sewer fees and 50 percent through stormwater fees.

The task force reasoned that the new fee would create equity in shouldering the burden, considering the fact that stormwater runoff is a major part of the CSO problem. According to a task force presentation delivered by Suslovic in March, an average Portland home annually contributes about 110,000 gallons to the combined sewer and stormwater system — around 70,000 gallons of sewer volume and 40,000 gallons of runoff from driveways, roofs and other impervious surfaces.

While a typical privately managed parking lot in the city contributes nothing in the way of sewage, it is responsible for about 3.5 million gallons of stormwater runoff annually, easily having a greater CSO impact than the average home. Yet, under the current system of billing, the parking lot owner pays nothing toward the CSO fixes while the average home over the next 15 years will see its annual annual sewer bills climbing up to around $850.

Under the recommended division of bills between sewer and stormwater, that same home in about 15 years would today pay $490 in sewer fees and $360 in stormwater fees per year, while the parking lot owners would pay $2,000 in stormwater fees and no sewer fees.

The big winners, according to the task force’s model, are large or industrial ratepayers. An average industrial sewer user might be looking at $435,000 per year in sewer bills 15 years out as its share of the CSO fix. But with the burden spread out to include stormwater contributors with no sewer inputs, the average industrial property would be billed about $260,000 — $250,000 in sewer fees and $9,500 in stormwater fees.

Under any scenario, the task force warns, the bills will be going up for everybody.

The task force estimates that a property or business owner currently paying $1,000 per year in sewer fees would see those bills raise to $1,900 by 2030 even if the city refused its Tier III obligations. Spreading the Tier III costs over 15 years through a series of bonds, which is the expected funding mechanism to be used, would push that same sewer user’s fees up to $2,840 annually by 2030.

Ian Houseal, Portland’s sustainability coordinator, said that while the city’s problem seems massive compared to Rockland, Philadelphia is facing $200 billion in costs to fix its CSO problems.

“Everybody’s wrestling with numbers that are almost unimaginable,” said Michael Bobinsky, director of Portland public services.

For those looking at the potential of skyrocketing bills, the sobering thought for Portlanders is that after Tier III, there very well might have to be a Tier IV.

“As a society, we’re past the point where for any reason — even economic reasons — it’s OK to dump raw sewage any more,” Casco Baykeeper Joe Payne said. “But then comes the rub that Portland’s spent $70 million so far and is going to spend another $170 million and they still won’t be done.”

Added Bobinsky: “We also recognize there are future environmental laws coming — ultimately, [the stormwater] may all have to go into the treatment plant. Where does that put us?”